A fuel cell is composed of a proton conductive film interposed between two catalyst layers, two gas diffusion layers, two bipolar plates, two current collectors, and two end plates. Two sides divided by a proton conductive film of a fuel cell (FC) belong to a anode (for hydrogen, reformatted gas, or methanol) and a cathode (for oxygen or atmosphere air), respectively. An oxidation reaction is performed at the anode, and a chemical reduction reaction is performed at the cathode. When hydrogen (or methanol) contacts a catalyst layer (e.g. platinum or alloys thereof) of the anode, the hydrogen is dissociated to proton and electron. The electron will flow from the anode to the cathode through an electrical bridge (connecting the anode and the cathode). The proton will penetrate through the proton conductive film from the anode to the cathode. Note that the proton conductive film is a wet film, the proton accompanying water molecules can penetrate therethrough, and other air molecules cannot penetrate therethrough. The catalyst of the cathode may combine the oxygen and the electron from the electrical bridge to form an oxygen ion. The oxygen ion will react with the proton penetrating through the proton conductive film to form a water molecule. The above reaction is an electrochemical oxidation and reduction reaction.
A proton exchange membrane fuel cell (PEMFC) or direct methanol fuel cell (DMFC) utilizing an electrochemical reaction may have a high efficiency, no pollution, fast response, and the like. The fuel cells can be series connected to enhance an electrical bridge voltage, and the electrode reaction area of the fuel cells can be increased to increase the current. An inexhaustible supply of oxygen supply (generally atmosphere air) may continuously provide electrical power to a device. As such, the fuel cells may serve as a small-scaled system power or designated as a big power plant, distributed power, or a motive power.